Evidence of global warming is most vividly seen in the melting polar ice caps. Researchers recently discovered how greenhouse gas emissions, particularly carbon dioxide (CO2), have caused tropical forest soil to have warmer temperatures as well. Tropical soils store about 33% of the world's carbon.
Before people began burning fossil fuels and the atmosphere trapped increasing levels of carbon dioxide, the Earth had a balanced carbon cycle with flowed in and out of the soil. Dead leaves and wood naturally emitted gases and were canceled out by microorganisms that consume carbon for energy such as microalgae in oceans.
According to a new study in the journal Nature, human activity that caused and accelerated climate change significantly impacted this natural balance. Soils containing carbon 'is more sensitive to warming than previously recognized,' said Andrew Nottingham from the University of Edinburgh's School of Geosciences.
Soil Sensitivity
The slight increase of tropical forest soils emitting carbon dioxide now largely affects gas concentrations in the atmosphere which contributes to climate change. Tropical forest soils emit carbon up to ten times more than greenhouse gas emissions from human activity.
Even a 1% imbalance of more carbon being released than absorbed by soils equal to 10% of manmade carbon emissions, explained Eric Davidson from the University of Maryland. Even a slight increase in surface temperature is disastrous, noted the team.
As the globe warms up by 33 degrees Fahrenheit (one degree Celsius), the consequence can be severe heatwaves, storms, rising sea levels, and droughts. Increased temperatures on land have been about 35.6 degrees (two degrees Celcius).
Nottingham and his team of researchers measured the forest soils of Barro Colorado Island in Panama with heating rods. Trees and oceans have been absorbing about 50% of excess carbon emissions that are anthropogenic (manmade).
Theoretical calculations predict that global tropical soils will be as warm as 39 degrees Fahrenheit (four degrees Celcius) by 2100. That would amount up to 65 billion tons of atmospheric carbon.
Nottingham explains that in 80 years, carbon emissions would be six times more than they are today from anthropogenic activity. Their experiments have been going on for two years but the theoretical figures 'could be an underestimation,' he said.
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Effects of Global Warming
Several studies have shown how excess atmospheric carbon has caused algal blooms or rapid increase of microalgae growth which has caused an imbalance in the ocean's food chain. Forests are also showing signs of 'carbon dioxide fatigue' from human activity.
According to the Global Forest Watch, a total of about 14,500 square miles of trees were cleared in 2019. Davidson explained that their results add to the evidence that forest soils are 'carbon sinks' as global warming worsens. Carbon dioxide is also released into the atmosphere when trees are cut down, which has been getting worse as more land is cleared for agriculture and urban expansion.
On the upside, the team's result creates 'a potentially substantial positive feedback to climate change,' the authors wrote. Researchers can develop better ways to preserve forests, cut human activity that cause greenhouse gas emissions, and reduce the rate of global warming.
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